It may sound a bit ridiculous, but Siri is a bit like a voice in your head that says things you don't really understand. It occurred to me when watching the iOS 6 feature video from the WWDC keynote presentation that there are a growing number of features built in to Siri that have no replicable function outside of Siri's voice interface. Obviously any time Siri interacts with a built in app it is interfacing with standard functionality. Some features however, such as Wolfram Alpha integration and the upcoming sports and movie functionality have no replicable direct interface elsewhere on the phone. The best case scenarios are dedicated apps from the App Store or web searches. This is fine, you might think, and you're right. This isn't a big deal or a hinderance in any significant way.
There is however, a little voice in that box that can automate things in a way the rest of the box can't, and that strikes me as a little odd.